Appraisal on Strength Characteristics of Alkali-Activated GGBFS with Low Concentrations of Sodium Hydroxide

This paper investigates the effect of low concentrations of sodium hydroxide (NaOH) and alkaline ratio (wt. of alkali silicate/alkali hydroxide) on the physical and mechanical properties of alkali-activated GGBFS. Parameters considered are activator concentration (1, 2, 3, 4, 5, 6, 7, 8, 9M) and alkaline ratio (1, 1.5, 2, 2.5, 3). Normal consistency, initial setting time and compressive strength tests were performed considering GGBFS as binder and alkaline solution as fluid medium with varying NaOH concentration and alkaline ratio. The obtained results indicated that change in NaOH concentration has significant effect on consistency, initial setting time and compressive strength of alkali-activated GGBFS. Change in alkaline ratio showed a significant effect in initial setting time and compressive strength of alkali-activated GGBFS. Compressive strength of mortar cubes cast with 4M NaOH with an alkaline ratio of 1.5 cured at room temperature produced a strength of 41 MPa at 28 days. XRD analysis indicated that increase in NaOH concentration resulted in increase in the intensity of albite peaks. SEM analysis indicated a complete dissolution of slag grains, and the gel was observed to be homogenous on slag particles at higher activator concentration.